That could have been very tricky, because Billie would have every right to feel it was her patch. But mercifully, because Billie is so generous and so lovely, and such a great actress and wonderful human being, frankly, it was such a joy to work with her, and such a pleasure. Dramatically, that’s what’s going on between the characters, because she’s having to rediscover this new man who’s the same man she knew, and how she feels about that. But very quickly, I think we established that relationship that they had was as deep, and ran even deeper ultimately.
David Tennant’s reply to “When you’re working with Billie (Piper), who’d had a pre-existing relationship with the other Doctor, how do you approach that as an actor, in terms of his feelings for her?”
Doctor: Well, if that’s what you want. I mean, it’s a bit soon. I had so many places I wanted to take you. The Fifteenth Broken Moon of the Medusa Cascade, the lightening skies of Cotter Palluni’s World, the diamond coral reefs of Kaata Flo Ko… Thank you. Thank you, Donna Noble. It’s been brilliant. You…you’ve saved my life in so many ways. You’re… you’re…you’re just popping home for a visit. That’s what you mean. Donna: You dumbo. Doctor: And then you’re coming back. Donna: Do you know what you are? A great, big, outer-space dunce. Doctor: Yeah.
I don’t know, I make a bit of music and call it Rose. I was in love with Rose/Billie. It made it quite easy. I mean Billie is an utterly, utterly adorable person and she has a smile like the sun coming out.